In the airline industry, it is a standard practice to compartmentalize the cargo which is be carried on board the larger aircraft. This is accomplished by separating the cargo into separate units and placing these units of cargo into individual containers which are commonly referred to as unit load devices (ULDs). Because of regulatory requirements, as well as practical considerations, the shape, size and weight of a ULD for each type of aircraft is standardized. Consequently, in order to design a ULD which will meet the standard requirements of the industry, and still effectively withstand the effects of a substantially large explosion emanating cargo held within the ULD, these limitations need to be considered.
Typically, ULD's are formed to include appropriately sloped surfaces that conform to the aircraft's fuselage when the ULD is placed in the aircraft's cargo compartment. Essentially, the ULD is formed from several panels which are joined together. Additionally, each ULD has an access hatch which allows for the placement cargo into and out of the ULD.
As a result of an explosion, a shock wave is produced which radiates outwardly in all directions from the explosion site. The shock wave is characterized by the formation of a relatively high pressure with a relatively short amount of time. When the shock wave encounters the interior portion of the ULD, the walls of the ULD experience stress. The flat portions of the walls are relatively strong and resist rupture. On the other hand, the highest stress concentrations which result from an explosion within the ULD tend to occur at the joints and around the door or hatch which covers the opening into the ULD. As a result of an explosion, these regions of localized high stress are usually the first to rupture or fail. An efficient structural design of the ULD would be such that no particular localized region would be especially susceptible to rupture or failure as a result of an internal explosion. An obvious means for achieving this would be to selectively strengthen or reinforce the localized regions where the highest stress concentrations occur by simply adding material at those regions. Such reinforcement material, however, is undesirable due to the substantial increase in weight.
Accordingly, there is a need in the art for a device or method which mitigates the effects of explosive forces occurring within a storage container or ULD, thereby containing the explosion and mitigating damage to the aircraft. It is desirable that the device is relatively light weight and relatively easy to manufacture and may be used to modify existing stores of storage containers and ULDs.